This invention relates to cable connecting apparatus and, more particularly, to such apparatus which can identify the type of cable connected thereto so as to make appropriate electrical connections to the wires within the cable.
In ring communications networks, such as, for example, those conforming to the IEEE Standard 802.5-1989 covering token ring networks, a plurality of line concentrators are connected together in a closed loop (i.e., a ring) by means of a trunk cable. Each concentrator includes a plurality of station ports to which a terminal, such as a computer, may be connected for communication over the ring with other such terminals in the network. Each concentrator also has a ring-in port and a ring-out port for interfacing with the medium (trunk cable) connected between the concentrators.
The trunk cable connecting the concentrators, as well as the station cable connecting the terminals to the station ports, typically includes four wires. Each of these wires must be connected in a defined manner to the terminals and the ports. While the wires within the cable have a fixed number as well as a fixed positional relationship, the cable itself can be selected from a number of different types. Thus, for example, the cable can be of the unshielded twisted pair type or the shielded twisted pair type. These different types of cable can have different electrical characteristics. For example, unshielded twisted pair cable has a characteristic impedance of one hundred ohms, whereas shielded twisted pair cable has a characteristic impedance of one hundred fifty ohms. It would be desirable to allow the equipment user to have the discretion to select the type of cable to be used in a particular installation. It would also be desirable to allow the user to be able to mix the types of cable within an installation, and even within a concentrator. It is therefore an object of the present invention to provide an arrangement for identifying the type of cable installed in a port.
It is a further object of this invention to provide an arrangement which, upon identifying the type of cable, provides suitable connections for that type of cable.